Method and apparatus for the automatic inspection of optically transmissive objects having a lens portion

Abstract

A system for inspecting intraocular lenses which utilizes a light source and an electronic camera for obtaining images of the lens under test. A series of masks is utilized during the obtaining of the images and includes a bright field mask which allows the transmission of light through the lens, a dark field mask which blocks a portion of the light which would normally pass through the lens and a transition mask which is constituted by fine stripes. A signal processor analyzes the images obtained utilizing the masks and provides an indication of predetermined defects in the lens.

What is claimed is:  
     
       1. Apparatus for determining defects in an optically transmissive object to be tested, said object having a lens portion, comprising: 
       (A) at least one camera for obtaining images of said object, said camera having an optical axis;  
       (B) at least one light source positioned along said axis for directing light at said camera;  
       (C) an object inspection location disposed between said camera and said light source for receiving said object;  
       (D) first and second masks positionable between said light source and said inspection location, with one of said masks being constructed and arranged to pass light from said light source through said object, the other of said masks having a light blocking portion and a light transmitting portion surrounding said light blocking portion, said light blocking portion being of a size and shape that, in the absence of defects, a dark background is totally formed in the image of said object being inspected, while in the presence of a defect, a corresponding bright region is created within said dark background;  
       (E) said camera being operable to obtain a first image of said object, with one of said masks in position between said light source and said inspection location, and a second image of said object with the other of said masks in position between said light source and said inspection location; and  
       (F) means for processing said first and second images of said object to obtain indications of predetermined defects.  
     
     
       2. Apparatus according to claim  1  wherein: 
       (A) said object a bi-convex lens.  
     
     
       3. Apparatus according to claim  2  wherein: 
       (A) said lens is an intraocular lens.  
     
     
       4. Apparatus according to claim  3  wherein: 
       (A) said intraocular lens includes on optical lens portion and a planar portion.  
     
     
       5. Apparatus according to claim  1  wherein: 
       (A) said light is diffused light.  
     
     
       6. Apparatus according to claim  5  wherein: 
       (A) said masks are operable to diffuse the light from said light source.  
     
     
       7. Apparatus according to claim  1  which additionally includes: 
       (A) a third mask positionable between said light source and said inspection location;  
       (B) said third mask having a series of alternating light blocking and light transmitting regions.  
     
     
       8. Apparatus according to claim  7  wherein: 
       (A) said third mask has a striped pattern thereon.  
     
     
       9. Apparatus according to claim  3  wherein: 
       (A) said intraocular lens includes first and second attachment loops; and which additionally includes:  
       (b) means for obtaining a side view image of said intraocular lens including said first and second loops.  
     
     
       10. Apparatus according to claim  9  wherein: 
       (A) said means for processing is operable to process said side view image for determining if each said attachment loop deviates from a predetermined position by an amount greater than a predetermined threshold.  
     
     
       11. Apparatus according to claim  1  wherein said apparatus includes: 
       (A) a single camera for obtaining images of said object;  
       (B) a single light source; and  
       (C) means for positioning individual objects to be tested between said single camera and said single light source.  
     
     
       12. Apparatus according to claim  11  wherein: 
       (A) said light source is a strobe light.  
     
     
       13. Apparatus for inspecting lenses, comprising: 
       (A) a camera for obtaining electronic images;  
       (B) a light source positioned to direct light toward said camera;  
       (C) a carrier for holding a plurality of said lenses to be inspected;  
       (D) a carrier drive for positioning individual ones of said plurality of lenses in the light path between said light source and said camera;  
       (E) a mask assembly including at least two masks, one of said masks allowing transmission of said light from said source through a positioned lens and the other for selectively blocking a portion of said light;  
       (F) a mask assembly drive for positioning said masks, one at a time, between said light source and said positioned lens;  
       (G) signal processing and control means being operable to control said carrier drive, said mask assembly drive and said camera for obtaining at least two electronic images of each said positioned lens; and  
       (H) said signal processing and control means being further operable to analyze said obtained images to provide an indication of predetermined defects in a said lens.  
     
     
       14. Apparatus according to claim  13  wherein: 
       (A) said mask assembly additionally includes a third mask;  
       (B) said third mask having a series of alternating light blocking and light transmitting regions.  
     
     
       15. Apparatus according to claim  14  wherein: 
       (A) said third mask has a striped pattern thereon.  
     
     
       16. Apparatus according to claim  15  wherein: 
       (A) said mask assembly includes a plurality of each of kind of said masks.  
     
     
       17. Apparatus according to claim  13  which includes: 
       (A) a pick-up device for removing a lens from said carrier.  
     
     
       18. Apparatus according to claim  13  wherein: 
       (A) said lens is an intraocular lens.  
     
     
       19. Apparatus according to claim  18  wherein: 
       (A) said intraocular lens includes first and second attachment loops; and which additionally includes:  
       (b) means for obtaining a side view image of said intraocular lens including said first and second loops.  
     
     
       20. Apparatus according to claim  19  wherein: 
       (A) said signal processing and control means is operable to process said side view image for determining if each said attachment loop deviates from a predetermined position by an amount greater than a predetermined threshold.  
     
     
       21. A method for inspecting optically transmissive objects having a lens portion, comprising the steps of: 
       (A) placing said object at an inspection location between a light source and an electronic camera which obtains images of said object;  
       (B) obtaining a first image of said object with one of a bright field or dark field mask in position between said light source and said object;  
       (C) obtaining a second image of said object with the other of said bright field or dark field mask in position between said light source and said object; and  
       (D) analyzing said obtained images to determine the presence of predetermined defects.  
     
     
       22. A method according to claim  21  wherein: 
       (A) said light source provides diffused light.  
     
     
       23. A method according to claim  21  wherein the method includes: 
       (A) obtaining a third image of said object with a third mask in position between said light source and said object, said third mask having a series of alternating light blocking and light transmitting regions.  
     
     
       24. A method according to claim  23  wherein: 
       (A) said light source provides diffused light.  
     
     
       25. A method according to claim  21  wherein: 
       (A) said object is an intraocular lens.  
     
     
       26. A method according to claim  21  wherein the method includes: 
       (A) separating said objects after said analyzing step into a plurality of categories including a pass category, a reject category and a rework category.  
     
     
       27. Apparatus according to claim  21  wherein: 
       (A) said light source is a strobe light.